Xen-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Roman Shaposhnik <roman@zededa.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: xen-devel@lists.xenproject.org, Kevin Tian <kevin.tian@intel.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Jan Beulich <jbeulich@suse.com>, Paul Durrant <paul@xen.org>
Subject: Re: [Xen-devel] PCIe IOMMU ACS support
Date: Thu, 26 Mar 2020 15:03:28 -0700
Message-ID: <CAMmSBy_oX34t5388xYUxUE_jE56bpy=wKAfujZvR1-zaehDs3g@mail.gmail.com> (raw)
In-Reply-To: <20200325110533.GC28601@Air-de-Roger>

On Wed, Mar 25, 2020 at 4:05 AM Roger Pau Monné <roger.pau@citrix.com> wrote:
>
> Adding the PCI and IOMMU maintainers.
>
> On Mon, Mar 23, 2020 at 01:55:01PM -0700, Roman Shaposhnik wrote:
> > Hi!
> >
> > I was going through how Xen support PCIe IOMMU ACS and
> > all I could find is this:
> >     https://github.com/xen-project/xen/blob/master/xen/drivers/passthrough/pci.c#L608
> > which looks to me as an attempt of enabling ACS opportunistically,
> > but still proceeding forward even if it fails.
>
> That's correct AFAICT. Xen will try to enable some features, but will
> proceed normally if ACS is not available, or if some of the features
> are not implemented.
>
> Are you looking to ensure that all devices on the system have a
> certain feature enabled?

My primary objective was to get some visibility into how Xen would
prevent two PCIe devices behind a common bridge from doing p2p
transactions (thus violating VM boundaries if those devices are
assigned to different domains).

It looks like Xen simply trusts the hardware.

> Can you provide some more details about what you expect of ACS
> handling?

I was actually surprised not to see IOMMU groups in the style of what
VFIO https://www.kernel.org/doc/Documentation/vfio.txt

Thanks,
Roman.


  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23 20:55 Roman Shaposhnik
2020-03-25 11:05 ` Roger Pau Monné
2020-03-26 22:03   ` Roman Shaposhnik [this message]
2020-03-27  9:12     ` Paul Durrant
2020-03-28  0:59       ` Roman Shaposhnik

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMmSBy_oX34t5388xYUxUE_jE56bpy=wKAfujZvR1-zaehDs3g@mail.gmail.com' \
    --to=roman@zededa.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=jbeulich@suse.com \
    --cc=kevin.tian@intel.com \
    --cc=paul@xen.org \
    --cc=roger.pau@citrix.com \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Xen-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/xen-devel/0 xen-devel/git/0.git
	git clone --mirror https://lore.kernel.org/xen-devel/1 xen-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 xen-devel xen-devel/ https://lore.kernel.org/xen-devel \
		xen-devel@lists.xenproject.org xen-devel@lists.xen.org
	public-inbox-index xen-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.xenproject.lists.xen-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git